It's an indicator of your reputation score. If someone gives reputation to a post you've made, your reputation score will increase and eventually that phrase will change as you "climb the ranks". Your current phrase is the default phrase

You can give reputation to a post by clicking the little image of a scale at the top/bottom of the post, depending on your forum skin. In the box that pops up you can leave a comment or motivation for the rep, if you wish. If you've received reputation, you can view the comments you've received and which posts was given reputation on the main page of your User CP.

Hope that helps!

Edit: Yes, cetra1 is correct, except for the fact that adding negative reputation has been disabled at EoFF, so your posts can never be rated as "bad".